1 /* IEEE754 floating point arithmetic 2 * double precision: common utilities 3 */ 4 /* 5 * MIPS floating point support 6 * Copyright (C) 1994-2000 Algorithmics Ltd. 7 * 8 * This program is free software; you can distribute it and/or modify it 9 * under the terms of the GNU General Public License (Version 2) as 10 * published by the Free Software Foundation. 11 * 12 * This program is distributed in the hope it will be useful, but WITHOUT 13 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 14 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 15 * for more details. 16 * 17 * You should have received a copy of the GNU General Public License along 18 * with this program; if not, write to the Free Software Foundation, Inc., 19 * 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 20 */ 21 22 #include "ieee754dp.h" 23 24 int ieee754dp_tint(union ieee754dp x) 25 { 26 u64 residue; 27 int round; 28 int sticky; 29 int odd; 30 31 COMPXDP; 32 33 ieee754_clearcx(); 34 35 EXPLODEXDP; 36 FLUSHXDP; 37 38 switch (xc) { 39 case IEEE754_CLASS_SNAN: 40 case IEEE754_CLASS_QNAN: 41 ieee754_setcx(IEEE754_INVALID_OPERATION); 42 return ieee754si_indef(); 43 44 case IEEE754_CLASS_INF: 45 ieee754_setcx(IEEE754_INVALID_OPERATION); 46 return ieee754si_overflow(xs); 47 48 case IEEE754_CLASS_ZERO: 49 return 0; 50 51 case IEEE754_CLASS_DNORM: 52 case IEEE754_CLASS_NORM: 53 break; 54 } 55 if (xe > 31) { 56 /* Set invalid. We will only use overflow for floating 57 point overflow */ 58 ieee754_setcx(IEEE754_INVALID_OPERATION); 59 return ieee754si_overflow(xs); 60 } 61 /* oh gawd */ 62 if (xe > DP_FBITS) { 63 xm <<= xe - DP_FBITS; 64 } else if (xe < DP_FBITS) { 65 if (xe < -1) { 66 residue = xm; 67 round = 0; 68 sticky = residue != 0; 69 xm = 0; 70 } else { 71 residue = xm << (64 - DP_FBITS + xe); 72 round = (residue >> 63) != 0; 73 sticky = (residue << 1) != 0; 74 xm >>= DP_FBITS - xe; 75 } 76 /* Note: At this point upper 32 bits of xm are guaranteed 77 to be zero */ 78 odd = (xm & 0x1) != 0x0; 79 switch (ieee754_csr.rm) { 80 case FPU_CSR_RN: 81 if (round && (sticky || odd)) 82 xm++; 83 break; 84 case FPU_CSR_RZ: 85 break; 86 case FPU_CSR_RU: /* toward +Infinity */ 87 if ((round || sticky) && !xs) 88 xm++; 89 break; 90 case FPU_CSR_RD: /* toward -Infinity */ 91 if ((round || sticky) && xs) 92 xm++; 93 break; 94 } 95 /* look for valid corner case 0x80000000 */ 96 if ((xm >> 31) != 0 && (xs == 0 || xm != 0x80000000)) { 97 /* This can happen after rounding */ 98 ieee754_setcx(IEEE754_INVALID_OPERATION); 99 return ieee754si_overflow(xs); 100 } 101 if (round || sticky) 102 ieee754_setcx(IEEE754_INEXACT); 103 } 104 if (xs) 105 return -xm; 106 else 107 return xm; 108 } 109